Higher Strength Gain Research Articles

Multi-experimental seismic analysis of low-rise thin reinforced concrete wall building with unconnected elastomeric isolators using real-time hybrid simulations

In response to the pressing need for housing and streamlining construction processes, the building industry has embraced innovative construction techniques. One such method, known as the Industrialized Housing Construction (IHC) system, departs from traditional framing systems by utilizing thin-reinforced concrete walls (TRCW). These TRCWs, characterized by high flowability and rapid strength gain, enable quick and efficient monolithic construction of walls and slabs. However, challenges have arisen regarding the structural behavior of these elements, potentially compromising their seismic performance. Given the significant seismic risk, there is a compelling need to develop resilient buildings by using this cost-efficient structural system. This study proposes the use of passive control systems such as base isolation to address this problem. While base isolation has proven effective in other countries, its feasibility in structures using TRCW and its performance during actual seismic events warrants further investigation. This paper presents an innovative approach using Multi-Axial Real-Time Hybrid Simulation (M-RTHS), which combines numerical and experimental components to gain deeper insights into the seismic response of low-rise TRCW buildings with base isolation using unconnected fiber-reinforced elastomeric isolators (U-FREIs). The methodology is detailed and includes the division of the structure into numerical and experimental segments and the use of transfer systems to replicate real seismic excitations, including those from El Centro (USA, 1940), Pizarro (Colombia, 2004), Chihuahua (Mexico, 2013), Loma Prieta (USA, 1989), and Kobe (Japan, 1995), with a maximum amplitude of 7.36 [Formula: see text] (0.75 g). The results highlight a remarkable reduction in upper structure floor drifts of over 57.47%, the characterization of the behavior and energy dissipation of each experimental specimen, and the optimal evaluation of M-RTHS. This research paves the way for improving the seismic resistance of buildings in regions prone to seismic activity, especially those using innovative construction methods such as TRCW.

Research on the long-term strength development of Datça Pozzolan-based geopolymer

This study examined the influence of long-term curing duration on the properties of geopoly- mers produced through the geopolymerization reaction between Datça Pozzolan and sodium silicate and potassium hydroxide solutions. The specimens were heat cured at 90 °C, 95±5% RH for 24 h initially and then kept under ambient conditions until the tests were conducted at 7, 90, and 365 days. The results showed that applied initial heat curing was appropriate to achieve high early and long-term strength. Geopolymer mortars with 12.5 M and 2.5 activator ratios had the lowest porosity (20.90%) and the highest ultrasound pulse velocity (UPV) (3.10 km/s), compressive strength (10.57 MPa), and flexural strength (5.20 MPa) after seven days. While the porosity of the identical specimens decreased by up to 15.77%, the UPV, compres- sive strength and flexural strength increased by 3.37 km/s, 15.32 MPa, and 6.06 MPa, respectively, after 365 days. The physical and mechanical improvement in the first 90 days exceeded 90–365 days. A higher rate of improvement was obtained when the activator ratio was low, i.e., the improvement decreased inversely as the sodium silicate content of the mortar increased. An increasing trend was observed in the plot of compressive strength as a function of UPV, and the slope values presented a strongly related linear function relation.

Effect of hybrid fibres on mechanical behaviour of magnesium oxychloride cement-based composites

Magnesium oxychloride cement (MOC) as a green cement has superior mechanical properties such as high strength and quick gain of early strength, however the inherent brittleness has limited its applications where ductility is crucial. To enhance the strength and ductility, a novel hybrid fibre-reinforced MOC-based composite (FRMOC) is developed for the first time using polyethylene (PE) fibres and basalt fibres (BF) to reinforce the MOC. A systematic investigation of the effect of fibre dosage on the flowability, rheological properties, compressive strength, and tensile properties of the developed FRMOC is conducted in this study. The results revealed that the addition of fibre reduces flowability while increasing the yield stress and plastic viscosity. The 1-day compressive strength of the FRMOC reached 68.2–85.4% of the corresponding value at 28 days, demonstrating its high early strength characteristic. The mix with 1.25% PE and 0.75% BF exhibited the maximum compressive strength at all curing ages. All the mixes consistently demonstrated excellent tensile strength and tensile strain capability (ductility), with the tensile strength and tensile strain capacity of 10.95 MPa and 4.41% achieved for the mix of 2% PE fibre, and 8.49 MPa and 2.43% for the mix of 1.25% PE and 0.75% BF respectively. Moreover, a decline in strength characteristics and strain capacity was observed as BF percentages increased. Scanning electron microscope (SEM) analysis was further employed to investigate the morphological changes in the FRMOC matrix at the microscale to discover the fibre reinforcing mechanism.

Preparation and performance of acrylic mortar repair material modified suitably by nano-fiber and nano-particle in low-temperature for high-strength gain applications in construction

Nano-particles and nano-fibers have a marked effect on the physico-mechanical properties of polymeric mortar. In this study, to further enhance the mechanical properties of acrylic repair materials used in extreme environments (−25 °C or even lower), we added nano-particles (SiC, Al2O3, B4C, Si3N4, Fe2O3, SiO2), nano-fibers (CFs, MW-CNTs), nano-sheets (GNP, MOS2) and one homemade three-dimensional (3D) nano-fibers SiC–OH@APTES-g-CFs-COOH, respectively, to the polymeric mortar. We investigated how the dimensionality, content and type affect the compressive strength and flexural strength of the acrylic mortar repair materials. Acrylic mortar specimens were prepared by mixing methyl methacrylate binder, aggregates, initiator, accelerator and different nano-particles in a standard cement mixer, which is placed in standard molds of 40mm × 40mm × 160 mm and kept in −25 °C. Compressive and flexural strength of the acrylic mortar repair materials were determined at 1h, 1d and 10d of curing. The carbon fibers were treated with γ-aminopropyltriethoxysilane (APTES), and the 3D nano-fibers SiC–OH@APTES-g-CFs-COOH were prepared. The Scanning electron microscopy (SEM) analysis indicated that a large number of SiC were uniformly and densely distributed on the surface of CFs. The mechanical strength results showed that almost all contents of nano-materials of any dimension used in this article could enhance the mechanical strength of the specimens. Notably, when 0.05 wt% SiC–OH@APTES-g-CFs-COOH was added, the compressive strength and flexural strength values of acrylic mortar specimens at 10d were improved by 41.16 % and 52.28 % than those of control specimens. The incorporation of 3D nano-fibers formed a mechanical engagement with the aggregates, which increased the contact area between the aggregates and 3D nano-fibers and the thickness of the contact layer inside the specimen, thus effectively transferring the stress when the specimen was subjected to the load, and enhance the interfacial properties between the substrate and the nanofillers. Among the explored nano-particles, the addition of Si3N4 could significantly improve the compressive and flexural strength of acrylic mortar. Compared with the control specimen, the compressive strength can be improved by 44.6 % and the flexural strength of acrylic mortar specimens can be improved by 76.2 % when the addition of Si3N4 was 0.3 % by weight. This article demonstrated the availability of nano-powders for improving the mechanical properties of polymeric mortar construction materials.

Influence of Dosage and Modulus on Soluble Sodium Silicate for Early Strength Development of Alkali-Activated Slag Cements

In world practice, the need for high-strength concrete with an intensive gain of early strength is due to an increase in requirements for characteristics of concrete and the desire to shorten the construction period. Alkali-activated cement, based on soluble sodium silicates (SSS), can demonstrate high strength and rapid gain due to the nano-modifying effect of amorphous silica present in SSS. However, the problem with the effective use of such cement compositions is unsatisfactory short setting times. This work investigates the effect of modifying admixtures on the structure formation of alkali-activated slag cement (AASC), its physical and mechanical properties depending on characteristics of SSS and the basicity of the aluminosilicate component (precursor), which was changed by the ratio of the ordinary Portland cement (OPC) clinker and granulated blast furnace slag (GBFS). A positive synergistic effect was noticed from glycerol and trisodium phosphate, as the components of a complex admixture, to control the setting of AASC. This resulted in extending the initial setting time from 1 to 5 min to the values of 21–72 min. The compressive strength of 21–26.3 MPa by 3 h, 36.5–43.4 MPa by 1 day, and 84.7–117.1 MPa by 28 days was obtained. Proper shrinkage deformations were equal to 0.47–0.6 mm/m. It was shown that with an increase in the basicity of the aluminosilicate component, the properties of AASC increased both in the early and late stages of hardening.

Understanding the Impact of KNO3 on the Carbonation Behavior of γ-C2S

γ-dicalcium silicate (γ-C2S) has received little attention in engineering applications due to its low hydraulicity, but it exhibits high carbonation reactivity and rapid strength gain with the added benefit of CO2 absorption, which demonstrates a vast potential for application in building materials. Included herein is an investigation of the promotion impact concerning a potassium nitrate (KNO3) solution on the carbonation behavior of γ-C2S, including the degree of carbonation (DOC), microstructure, and mechanical properties. Results show DOC increases when KNO3 is introduced into the system, and as the concentration of KNO3 solution rises, DOC can reach as high as 60%, compared with 49% without KNO3; The porosity of the system is reduced by 37%; The compressive strength after 24 h of accelerated carbonation, with the KNO3 concentration of 2 mol/L, reaches 90 MPa—34% higher than that of the blank group. The presence of KNO3 solution contributes to retaining water—the dominant position for carbonation—in the sample and reducing evaporation, thus prolonging the carbonation time. The increased volume of carbonation products densifies the whole system as the reaction occurs. A barrier to γ-C2S dissolution, the amorphous silica layer wrapping on the surface of grains, is destroyed due to the introduction of K+, facilitating the continuous dissolution of silicate. The incorporation of KNO3 results in a larger crystal in size and more regularity in shape. Prolongation of the reaction duration allows for more adequate crystal growth, resulting in compacts with superior mechanical properties.

Effect of composition of geopolymer composites containing fly ash and waste glass powder on their durability and resistivity demonstrated in presence of a nanocarbon additive in a form of graphene

The objective of this study was to obtain a geopolymer composite with semi-conductive or conductive properties for self-control of abnormal symptoms caused by damages to its microstructure. For that purpose effects of different content of fly ash, waste glass powder, as well as two types of graphene and hydrophilic and hydrophobic nanosilica on electrical, physical and mechanical properties were tested. Measurements of resistivity showed the capacity for electrical charge flow in composites, which depended on their composition and products of the geopolymer hardening process. Based on results of the electrical charge flow intensity and observations of geopolymer composite microstructure by means of XRD and scanning microscopy, a possible course of the electrical conductivity mechanism in geopolymer materials was indicated. It was found that geopolymer composites containing fly ash, as well as addition of graphene and hydrophobic nanosilica, showed the most favourable electrical charge conductivity parameters and the highest strength gain.

Superplasticizer compatibility with cement properties – A study

Portland cement has been the conventional building material down through the ages. But with passing decades materials other than cement were being added to the cementitious system from outside to improve or modify its mix properties. The role of these materials was of varying degrees starting from water reducing to viscosity modifying to shrinkage reducing to being pozzolanic to reducers or accelerators. The existing literature survey suggests that a very high range water reducer or Superplasticizers can make a cementitious mix flowable at a low water-cement ratio without segregation and bleeding – the most basic principle of a fresh cementitious mix. Portland cement without admixtures in contact with water tends to flocculate resulting in agglomeration of particles in the mix thus making the system non-lubricating. Our paper discusses the various effects of Superplasticizers on the properties of cementitious mixes and the contribution of its constituent mineral phases. More recently, a new type of Superplasticizers based on 4th generation polymers are preferred in terms of lower slump loss at a low water-cement ratio.Our paper reports the addition of high performing superplasticizer -Poly Carboxylate Ether in cement composites as per Indian Standards has resulted in a denser cementitious matrix and higher strength gain at longer terms compared to normal superplasticizers.

Continuous Reinforced Concrete Beams Strengthened with Fabric-Reinforced Cementitious Matrix: Experimental Investigation and Numerical Simulation

This paper aims to examine the nonlinear flexural behavior of continuous RC beam specimens strengthened with fabric-reinforced cementitious matrix (FRCM) composites through experimental testing and numerical modeling. A total of nine two-span RC beam specimens were constructed and tested. Test parameters included the type of FRCM (carbon (C-FRCM) and polyparaphenylene benzobisoxazole (PBO-FRCM)), location of strengthening (sagging and hogging regions) and number of FRCM layers (two and four layers). Test results indicated that sagging strengthening resulted in a strength gain in the range of 17 to 29%, whereas hogging strengthening increased the load capacity by 9 to 17%. The use of C-FRCM resulted in a higher strength gain than that provided by PBO-FRCM composites. Specimens strengthened with PBO-FRCM exhibited, however, higher ductility and deformational capacity than those of their counterparts strengthened with C-FRCM. Doubling the number of FRCM layers resulted in no or insignificant increase in the load capacity but reduced the beam ductility. Specimens strengthened in the sagging regions exhibited moment redistribution ratios of 13 to 26% between the hogging and sagging regions. Insignificant moment redistribution was recorded for the specimens strengthened in the hogging region. Three-dimensional (3D) numerical simulation models, with and without an interfacial bond-slip law at the fabric–matrix interface, were developed. The inclusion of the bond-slip law in the modeling had an insignificant effect on predicted response. Although the models tended to underestimate the deflection, the predicted load capacities were within a 12% error band. Numerical findings were in agreement with those obtained from laboratory testing.

Investigation of waste clay brick as partial replacement of geopolymer binders for rigid pavement application

Waste clay brick (WCB) is identified as a feasible alternative cementitious material for producing geopolymer binders to replace ordinary Portland cement (OPC). This study investigated mechanical properties and environmental impacts of one-part geopolymer binders at ambient curing conditions, employing binary blends of WCB with fly ash or slag, while using anhydrous solid sodium metasilicate as the sole activator. WCB was replaced separately with fly ash and slag at 20%, 40%, 60% and 80% by mass to obtain the aluminosilicate precursors. Combination of the aluminosilicate precursors and the solid activator was considered as the total binder. The effect of the alkali activator content, particle size and water-to-binder ratio on compressive strength development were investigated. The strengths of the geopolymers were compared with minimum concrete strength requirements indicated in Australian pavement design guidelines and American Association of State Highway and Transportation Officials (AASHTO) guidelines. The experimental results indicated an optimum activator content of 10% by mass of the total binder for all binary geopolymer systems. Compared to WCB alone and WCB-fly ash blends, binary geopolymer systems of WCB-slag blends showed higher compressive strengths. WCB-slag blends showed high early strength gain and achieved more than 22% and 48% of its corresponding 28-day strength within 24 h and 72 h, respectively. Highest 28-day compressive strength of 81.8 MPa was achieved for the binder with 40% WCB and 60% slag in the precursor. The strength further improved to 96.8 MPa by reducing WCB particle size from 150 µm-passing to 75 µm-passing. Additionally, the environmental impacts associated with the different blends were evaluated considering carbon dioxide emission and energy consumption during their production. These values were subsequently compared with those of OPC manufacturing. The comparison showed that WCB based geopolymer binders can reduce carbon emissions up to 78% and energy consumption up to 85%.

Higher strength gain after hypoxic vs normoxic resistance training despite no changes in muscle thickness and fractional protein synthetic rate.

Acute hypoxia has previously been suggested to potentiate resistance training-induced hypertrophy by activating satellite cell-dependent myogenesis rather than an improvement in protein balance in human. Here, we tested this hypothesis after a 4-week hypoxic vs normoxic resistance training protocol. For that purpose, 19 physically active male subjects were recruited to perform 6 sets of 10 repetitions of a one-leg knee extension exercise at 80% 1-RM 3 times/week for 4weeks in normoxia (FiO2 : 0.21; n=9) or in hypoxia (FiO2 : 0.135, n=10). Blood and skeletal muscle samples were taken before and after the training period. Muscle fractional protein synthetic rate was measured over the whole period by deuterium incorporation into the protein pool and muscle thickness by ultrasound. At the end of the training protocol, the strength gain was higher in the hypoxic vs the normoxic group despite no changes in muscle thickness and in the fractional protein synthetic rate. Only early myogenesis, as assessed by higher MyoD and Myf5 mRNA levels, appeared to be enhanced by hypoxia compared to normoxia. No effects were found on myosin heavy chain expression, markers of oxidative metabolism and lactate transport in the skeletal muscle. Though the present study failed to unravel clearly the mechanisms by which hypoxic resistance training is particularly potent to increase muscle strength, it is important message to keep in mind that this training strategy could be effective for all athletes looking at developing and optimizing their maximal muscle strength.

Stabilization of Indian peat using alkali-activated ground granulated blast furnace slag

Peat is an exceptionally problematic soil for construction purposes and is often stabilized by traditional stabilizers (like cement), which emits 0.95-ton carbon dioxide (CO2) per ton of cement during their production. Alkali-activated ground granulated blast furnace slag (GGBS) with its low carbon dioxide (approximately 0.07-ton CO2) emissions and higher strength gain provides a promising substitute to traditional stabilizers. Therefore, this study presents the viability of alkali-activated GGBS-stabilized Indian peat. The three types of peats (sapric, fibric, and hemic) were collected to cover a wide range of variations of fibre (6–73%) and organic content (21–79%). The sodium hydroxide (NaOH) molarities (M) of 6, 9, 12, and 15 were used to activate specimens, with GGBS percentages of 10, 20, and 30% by weight of dry peat and alkali/binder ratios of 0.5, 0.7, and 0.9. The test results show that the UCS of peat-GGBS depends on the molarity of NaOH, A/B, electrical conductivity (EC), pH, curing period, and organic content of the peat-GGBS matrix. The optimum combination for the peat-GGBS blend is 20% GGBS, NaOH molarity of 9, and A/B ratio of 0.7. Furthermore, it was found that UCS increases with the curing period and decreases with organic content (OC). The formation of aluminium silicate, sodium aluminosilicate, and potassium aluminosilicate responsible for strength gain is confirmed by XRD. The FESEM micrographs reveal that these products result in the filling of pore spaces to form a smooth and dense soil-binder matrix.

Investigation of Rheological Behavior of Self-Compacting and High Performance Composite Concretes

This work describes proposed experimental methods for the characterization of concrete in fresh and hardened state, with the purpose of contributing to the experimental characterization of concrete. The main objective was to identify the rheological behavior of high performance (HP) and self-compacting (SC) concretes. Initially, a ordinary concrete composition was proposed, from which, silica fume (5, 10 and 15% in mass) and superplasticizer (0.6% in mass) were added to obtain HPC and SCC. Furthermore, for the self-compacting concretes, a modification in granular skeleton was proposed, with a reduction of total aggregate percentage by 22.73% in relation to the other compositions. The interference of these modifications was evaluated on the behavior of fresh concrete though the flow and slump test and hardened concrete through mechanical properties. The results showed that the modification in the granular skeleton of ordinary concrete contributed directly to the reduction of inertia factors of SCC, favoring the mobility conditions. For both self-compacting and high performance concretes, consistency and mechanical strength gain over ordinary concrete were influenced when the silica fume and superplasticizer concentration was increased, limiting your properties gains to these additions.

Application of recycled tire polymer fibers and glass fibers for clay reinforcement

Soil reinforcement with fibers is a simple, efficient and low-cost (especially by incorporating waste or recycled fibers) technique for enhancing mechanical characteristics of soft soils. This experimental study investigates the effects of recycled tire polymer fibers (RTPF) and glass fibers (GF) on enhancing the strength/deformation properties of clays. A series of compaction, unconfined compression and direct shear tests were performed on precisely prepared composite soils comprising clay, with different amounts (i.e. 0.5, 1.0 and 1.5%) of RTPF and GF having varying lengths (5 and 10 mm). Laboratory findings indicated that the composite soils have lower dry density and higher optimum moisture content as compared to the clay. Both unconfined compression and shear strength test results on composite soils implied that while adding fibers increased the materials’ ductility, there was an optimal percentage of fibers (0.5% for RTPF and 1.0% for GF) causing the highest strength gain, beyond which strength decreased. Concerning the shear strength parameters, i.e. cohesion intercept and internal friction angle, the fiber inclusion was particularly influential in increasing cohesion, whereas changes in internal friction angle were minimal. Moreover, the shorter fibers (5 mm) were generally more efficient in reinforcing the clay. The fiber improved composite soils have a better ductility and load-bearing capacity compared to parent soils that can be beneficial in the construction of pavement and railway substructure, liners, small fills/dikes, backfills around pipes, and slope protections.

STUDY ON THE PERFORMANCE OF SHALLOW SOIL MIXING WITH CEMENT

Shallow Soil Mixing (SSM) method with a low dosage of cement can be used to create a sufficiently strong platform for quick access onto grounds that have been recently reclaimed with soft clays. The effectiveness of the SSM method is dependent on the type, dosage and dosing method of cement, the mixing blade design, and the mixing sequence. Hence, a laboratory-scale SSM apparatus was developed to simulate SSM in the field. The early strength development and uniformity of Cement Mixed Soil (CMS) were evaluated by taking into consideration (a) Type of cement: CEM I vs CEM III/A, (b) Dosage of cement: 7% vs 3%, (c) Dosing method: 1-layer vs 2-layer mixing, and (d) Mixing blade design: without overlap between mixing blades vs overlapped mixing blades. Shear strength test results demonstrated that the shear strength development of CMS at an early stage is affected by the type, dosage, and dosing method of cement, while the uniformity of the CMS is affected by the dosage and dosing method of cement and the mixing blade design. From the laboratory test results, it is recommended that CEM III/A cement with 7% cement dosage, 2-layer of dosing method and overlapped mixing blades design parameters be used for SSM in the field to achieve high early strength gain and good uniformity cement soil mix.

Impact of CNTs' treatment, length and weight fraction on ordinary concrete mechanical properties

This study investigates the effect of the treatment, length and weight fraction parameters of multi-wall carbon nanotubes (MWCNT) on the mechanical properties of concrete. Mixes with various CNTs’ amounts ranging between 0.03 and 0.5 wt% were prepared using treated and untreated short and long CNTs. The flexural, compressive, and tensile strengths of the concrete composites were determined after 28, 56 and 90 days of curing. After that, the microstructures of the samples were investigated using a scanning electron microscope (SEM). The results were then analyzed using statistical t-tests to evaluate the significance of adding CNTs to concrete. The results showed that 0.03% long-treated CNTs increased compressive, flexural, and tensile strengths of ordinary concrete by 23, 29 and 20%, respectively. CNTs’ weight fraction and treatment parameters showed a noticeable effect on concrete strength. Concrete batches with 0.03 and 0.08% treated CNTs and 0.08% non-treated CNTs’ showed a relatively higher strength gain. Statistical t-tests confirmed that incorporating 0.03% long-treated CNTs into concrete had significantly improved compressive, flexural and tensile strengths. The analysis also showed that using fewer CNTs’ amounts of 0.03 and 0.08 wt% yielded higher strength results irrespective of the nanofilament treatment.

Effect of soda-lime glass powder on alkali-activated binders: Rheology, strength and microstructure characterization

Alkali-activated binders (AABs) have the potential to consume various types of cementitious waste materials, including coal ashes, municipal solid waste incinerator ash, palm-oil fuel ash, steel slags, mine tailings, cement kiln dust, ceramic tile residue, rice husk ash, and waste glass. This paper presents a study of alkali-activated cement paste produced with the substitution of the cementitious waste material soda-lime glass, which makes up the major proportion of the general glass waste stream. In the alkali-activated cement paste, crushed soda-lime glass powder (CG) was used as a replacement for class F fly ash (FA) from 0 to 30% by total solid weight, keeping the ground granulated blast furnace slag (GGBFS) content constant at 50%. The influence of activator molarity (4–8 M), alkaline liquid/solid binder (L/S) ratio (0.4–0.5) and different curing conditions (ambient air curing, wet curing, and short-term heat curing) on the rheology, strength, and microstructure of CG-substituted AABs was investigated and optimum conditions are suggested. According to the experimental results, both the workability and strength (compressive and tensile) of the AAB gradually increased with increasing level of substitution of FA by CG. Significant improvement in flow and setting time was seen with the addition of CG, even in mixtures with a low L/S ratio of 0.4. Both ambient and wet curing had more influence on the strength gain of AABs, especially after 28 days. Short-term heat curing resulted in high early strength gain. The dissolution of CG increased with increasing molarity (from 4 to 8 M) of the alkaline solution, which improved both strength and microstructure with curing time. Morphological and elemental analysis indicated an improvement of the microstructure of AABs due to the increased formation of calcium-dominant hydration products and hence reduced porosity with the substitution of CG. However, undissolved large-sized CG particles agglomerated in the binder without participating in the alkaline reactions. These agglomerated particles may induce micro-cracks due to weak bonding between the cement matrix and the smooth CG interface, which reduces the durability of AABs. Therefore, the inclusion of waste soda-lime glass powder with a mean diameter of 10–15 µm as a precursor in FA/GGBFS-based AAB as a replacement for FA is feasible and provides a good solution for waste material recycling.

Fresh, Strength and Durability Characteristics of Binary and Ternary Blended Self Compacting Concrete

Paper Mineral admixtures being the economical alternatives to Ordinary Portland Cement (OPC) for various normal and special concretes induce desirable properties to concrete such as higher flow, low heat of hydration, higher strength gain and enhanced durability. Ground granulated blast furnace slag(GGBFS) being one of the largely used mineral admixture alongside Fly Ash as supplementary cementitious material in concrete contributes to enhanced durability properties and low heat of hydration. Various replacement percentages of GGBS at 30%, 40%, 50% and 60% are used in binary blended Self compacting concrete(SCC) in the present study. At 40% replacement level, SCC exhibited improved workability, strength and durability properties. Alccofine(Ultrafine GGBS) used in ternary blended SCC enhanced early strength gain without affecting workability of SCC to a significant extent.

Strength development and prediction of calcium sulfoaluminate treated sand with optimized gypsum for replacing OPC in ground improvement

For ground improvement, the use of calcium sulfoaluminate (CSA) cement, which has lower carbon footprint is examined as an alternate to ordinary Portland cement (OPC). The use of additives like lime or fly ash results only in partial replacement of OPC, while complete replacement of OPC is possible using CSA binder. For CSA-treated sand, the optimized gypsum content is experimentally determined as 30% since it enables high initial strength and durable strength gain. In both wet and dry curing, CSA-treated sand has significantly high strength gain compared to OPC. Finally, a unified strength prediction model for cemented soil is proposed for wide ranges of cement and soil types.

Study of properties of fly ash cements

Abstract Laboratory experiments in the cement manufacturer of LafargeHolcim- Oujda in Morocco were conducted to investigate the effect of addition of fly ash on Ordinary Portland Cement OPC. In this study a portion of this cement was replaced by fly ash with different dosages (15%, 25%, 35% and 45%). The results of these experiments showed technical benefits of fly ash cements compared to Portland cements: - Less water demand, - Less heat of hydration and less risk of early age cracking and High late strength gain. However the inferior property of fly ash cements is lower early strength.